¿ªÔÆÌåÓý

  1. BITX20
  2. Messages
Expanded Topics Messages Polls
Date
Re: Different display issues

Jack Purdum
 

Hi Darryl:

The Mega2560 Pro Mini seems to be running fine and, like I said, we made this PCB for an antenna analyzer and it seems to be working great using both the AD9850 and the Pro Mini. As I've admitted many times before, I'm a software guy and the finer points of the electronics is just a little short of voodoo to me...but I'm trying. Farrukh Zia (K2ZIA) is a professor in the EE department at The City College of NY and designed the board, but I'm using it for a purpose outside of his design. Obviously, I using it inappropriately...my bad!

That said, I will give these suggestions a try. I already have added some caps to the power rails, but perhaps it still needs more. I still have the flicker and noise.

I'm passing your ideas onto Farrukh, as we are making a new PCB for this project as I think my club will be doing a build of this. The new board brings out more of the I/O lines so the Mega is more hackable than it is now. I have a few more things I want to hang on the rig and will need access to more pins that I have currently. Your ideas may influence his design.

I'll keep you posted. Again, thanks!

Jack, W8TEE


From: Darryl Harvey <darryl@...>
To: [email protected]
Sent: Tuesday, January 24, 2017 7:35 AM
Subject: Re: [BITX20] Different display issues

Jack,?

Just did a bit of checking and the specs for the Mega2560 Pro Mini says that it needs a 7-12V supply. ?Your circuit shows this as 6.6v.
This may be a little low of the onboard 5V regulator to function correctly?

Can you bump this supply up a bit ?

Also, your circuit doesn¡¯t show any decoupling caps before or after your power regulator.
you should have some 100nf Caps, and some ~10uF caps for some decoupling before and after the supply regulator.
Also with your circuit and the diodes to drop it down to 5v, again, no decoupling caps.?
and again down to 3.6v via diodes you have no decoupling..

Are you sure your AD9850 is 3.3v?? ?Mine is 5v.

Either way, again, you can power this from the 3.3v output from the Mega2560 Pro Mini 3.3v Output.

What I would do: ?Raise you supply voltage to 8V, supply the Mega2560 Pro Mini Vin this 8V. (provide decoupling caps before and after the regulator)
or if your supply voltage never goes above 12V, feed the 12 V into Vin on the Mega2560 Pro Mini. (again, decoupling caps never hurt)
From the 5V output of the Mega2560 Pro Mini, power the SWR Bridge, AD9850 and TFT display.
And if your DDS is 3.3v, power this from the 3.3v output of the Mega2560 Pro Mini.

If you do what I suggest above, you should be ok. (Assuming you have power problems - which it looks like)

Hope this makes sense.
let me know how you go.
Good luck
Darryl?
VK3DAZ


On 24 Jan 2017, at 11:26 am, Jack Purdum via Groups.Io <econjack@...> wrote:

Thanks Darryl...that gives me something to check into...it's appreciated!

Jack, W8TEE

From: Darryl Harvey <darryl@...>
To: [email protected]
Sent: Monday, January 23, 2017 3:36 PM
Subject: Re: [BITX20] Different display issues

Hi Jack,
I have been battling "noise clicks" for some time now in my DDS. I have tracked it to the i2c bus SDA data being injected in the power rail by my OLED display, the bitx is so sensitive it acts on this noise, my Mst3 with the exact same DDS doesn't have this problem.?

Anyway, the only way I could reduce this noise after many tests and redesigns was to put a D.C.-D.C. Isolator in the power rail for my OLED display. it didn't remove it 100%, more like around 95% - but at least it was usable.?
A simple voltage regulator (7805) and associated filter caps and even chokes didn't help.?

Even though the clicks occur when moving the encoder, it was the display updates causing the noise for me. ?When I moved to a TFT or LCD display I didn't have this issue, but check that your voltage supply to the DDS is not under load, that could cause some noise on updates.

Hope this helps
Darryl
VK3DAZ


On 24 Jan 2017, at 6:39 am, Jack Purdum via Groups.Io <econjack@...> wrote:

All:

I have my B40 with Raduino display and it works as advertised. I am now trying to add my TFT display and DDS VFO, which is a AD9850, more-or-less the same as the VFO in the Forty-9er article (March, 2016 QST). I am using a rotary encoder to change the frequency, again the same as before. The processor is a Mega 2560 Pro Mini; too many things going on for a Nano. I've used the TFT display, DDS, and Mega boards on an antenna analyzer project and had no issues. (Schematic attached, the SWR bridge is omitted.) However, on the B40, any movement of the encoder can be "heard" in the receiver audio. Also, there is a slight dimming, or flicker, of the display when rotating the encoder.?

As I've said many times before, I'm a software guy so the EE stuff leaves me not knowing where to begin. Any ideas sincerely appreciated.


Jack, W8TEE
<Figure33.jpg>
Re: power for qrp-labs dds

Jack Purdum
 

Hi Ryan:?

I think that's my next step. The buck converter worked fine on the Forty-9er, but I think this receiver is more sensitive.

Thanks!

Jack, W8TEE


From: Ryan Flowers <geocrasher@...>
To: [email protected]
Sent: Tuesday, January 24, 2017 1:56 AM
Subject: Re: [BITX20] power for qrp-labs dds

I just used a 7805 regulator connected to 12v. Works fine so far. Yes, you lose a little power in heat, so it's not as efficient as a buck converter, but I don't consider it an issue for my use.
Hope this helps!
Ryan KC7RYS
Re: Different display issues

Jack Purdum
 

I already have debounce caps in place.

Jack, W8TEE


From: Sandeep Lohia <sandeeplohia12@...>
To: [email protected]
Sent: Monday, January 23, 2017 11:26 PM
Subject: Re: [BITX20] Different display issues

can also use 100nf caps directly installed on coder to ground...
'Repair & Reuse or Recycle E-Waste'
Re: Different display issues

 

¿ªÔÆÌåÓý

Jack,?

Just did a bit of checking and the specs for the Mega2560 Pro Mini says that it needs a 7-12V supply. ?Your circuit shows this as 6.6v.
This may be a little low of the onboard 5V regulator to function correctly?

Can you bump this supply up a bit ?

Also, your circuit doesn¡¯t show any decoupling caps before or after your power regulator.
you should have some 100nf Caps, and some ~10uF caps for some decoupling before and after the supply regulator.
Also with your circuit and the diodes to drop it down to 5v, again, no decoupling caps.?
and again down to 3.6v via diodes you have no decoupling..

Are you sure your AD9850 is 3.3v?? ?Mine is 5v.

Either way, again, you can power this from the 3.3v output from the Mega2560 Pro Mini 3.3v Output.

What I would do: ?Raise you supply voltage to 8V, supply the Mega2560 Pro Mini Vin this 8V. (provide decoupling caps before and after the regulator)
or if your supply voltage never goes above 12V, feed the 12 V into Vin on the Mega2560 Pro Mini. (again, decoupling caps never hurt)
From the 5V output of the Mega2560 Pro Mini, power the SWR Bridge, AD9850 and TFT display.
And if your DDS is 3.3v, power this from the 3.3v output of the Mega2560 Pro Mini.

If you do what I suggest above, you should be ok. (Assuming you have power problems - which it looks like)

Hope this makes sense.
let me know how you go.
Good luck
Darryl?
VK3DAZ


On 24 Jan 2017, at 11:26 am, Jack Purdum via Groups.Io <econjack@...> wrote:

Thanks Darryl...that gives me something to check into...it's appreciated!

Jack, W8TEE

From: Darryl Harvey <darryl@...>
To: [email protected]
Sent: Monday, January 23, 2017 3:36 PM
Subject: Re: [BITX20] Different display issues

Hi Jack,
I have been battling "noise clicks" for some time now in my DDS. I have tracked it to the i2c bus SDA data being injected in the power rail by my OLED display, the bitx is so sensitive it acts on this noise, my Mst3 with the exact same DDS doesn't have this problem.?

Anyway, the only way I could reduce this noise after many tests and redesigns was to put a D.C.-D.C. Isolator in the power rail for my OLED display. it didn't remove it 100%, more like around 95% - but at least it was usable.?
A simple voltage regulator (7805) and associated filter caps and even chokes didn't help.?

Even though the clicks occur when moving the encoder, it was the display updates causing the noise for me. ?When I moved to a TFT or LCD display I didn't have this issue, but check that your voltage supply to the DDS is not under load, that could cause some noise on updates.

Hope this helps
Darryl
VK3DAZ


On 24 Jan 2017, at 6:39 am, Jack Purdum via Groups.Io <econjack@...> wrote:

All:

I have my B40 with Raduino display and it works as advertised. I am now trying to add my TFT display and DDS VFO, which is a AD9850, more-or-less the same as the VFO in the Forty-9er article (March, 2016 QST). I am using a rotary encoder to change the frequency, again the same as before. The processor is a Mega 2560 Pro Mini; too many things going on for a Nano. I've used the TFT display, DDS, and Mega boards on an antenna analyzer project and had no issues. (Schematic attached, the SWR bridge is omitted.) However, on the B40, any movement of the encoder can be "heard" in the receiver audio. Also, there is a slight dimming, or flicker, of the display when rotating the encoder.?

As I've said many times before, I'm a software guy so the EE stuff leaves me not knowing where to begin. Any ideas sincerely appreciated.


Jack, W8TEE
<Figure33.jpg>
Re: power for qrp-labs dds

 

I just used a 7805 regulator connected to 12v. Works fine so far. Yes, you lose a little power in heat, so it's not as efficient as a buck converter, but I don't consider it an issue for my use.

Hope this helps!

Ryan KC7RYS
Re: Different display issues

 

can also use 100nf caps directly installed on coder to ground...

'Repair & Reuse or Recycle E-Waste'
BitX40 Frequency?

Jim Schliestett
 

¿ªÔÆÌåÓý

Is there a frequency on 40M where BitX folks hang out? I would like to make some BitX40 to BitX40 contacts. By the way, I worked 4M1K and ZS6CCY with my BitX40 running 5W from Georgia during the NAQP contest last weekend. It works!

?

Jim, K4AEK
Re: BC849 replacement

 

Thanks Ashhar. The turns of toroid are not shorted, so must be a bad transistor.

73

Ken

On Mon, Jan 23, 2017 at 8:48 PM, Ashhar Farhan <farhanbox@...> wrote:
the transistors of bitx40 are mmbt3904. kicad didnt have a footprint for them, so i usd th bc849 footprint instead

On 24-Jan-2017 7:11 am, "Ken" <chase8043@...> wrote:
Thanks Marco. Yes I did mean?MMBT3904. It's been a long day.

73 Ken

On Mon, Jan 23, 2017 at 8:34 PM, M Garza <mgarza896@...> wrote:
Ken,
Did you mean?MMBT3904?? If so, yes, you should be able to sub it in.? Pin out is the same.? You are right, the specs are better on the 3904.

Marco - KG5PRT



On Mon, Jan 23, 2017 at 7:24 PM, Ken <chase8043@...> wrote:
I need to replace one of the BC849 transistors in the VFO circuit.

I have on hand MMBT394, I assume I can use them? Looks like they have better ratings.

73

Ken VA3ABN
Re: BC849 replacement

 

the transistors of bitx40 are mmbt3904. kicad didnt have a footprint for them, so i usd th bc849 footprint instead

On 24-Jan-2017 7:11 am, "Ken" <chase8043@...> wrote:
Thanks Marco. Yes I did mean?MMBT3904. It's been a long day.

73 Ken

On Mon, Jan 23, 2017 at 8:34 PM, M Garza <mgarza896@...> wrote:
Ken,
Did you mean?MMBT3904?? If so, yes, you should be able to sub it in.? Pin out is the same.? You are right, the specs are better on the 3904.

Marco - KG5PRT



On Mon, Jan 23, 2017 at 7:24 PM, Ken <chase8043@...> wrote:
I need to replace one of the BC849 transistors in the VFO circuit.

I have on hand MMBT394, I assume I can use them? Looks like they have better ratings.

73

Ken VA3ABN
Re: BC849 replacement

 

Thanks Marco. Yes I did mean?MMBT3904. It's been a long day.

73 Ken

On Mon, Jan 23, 2017 at 8:34 PM, M Garza <mgarza896@...> wrote:
Ken,
Did you mean?MMBT3904?? If so, yes, you should be able to sub it in.? Pin out is the same.? You are right, the specs are better on the 3904.

Marco - KG5PRT



On Mon, Jan 23, 2017 at 7:24 PM, Ken <chase8043@...> wrote:
I need to replace one of the BC849 transistors in the VFO circuit.

I have on hand MMBT394, I assume I can use them? Looks like they have better ratings.

73

Ken VA3ABN
Re: BC849 replacement

M Garza
 

Ken,
Did you mean?MMBT3904?? If so, yes, you should be able to sub it in.? Pin out is the same.? You are right, the specs are better on the 3904.

Marco - KG5PRT



On Mon, Jan 23, 2017 at 7:24 PM, Ken <chase8043@...> wrote:
I need to replace one of the BC849 transistors in the VFO circuit.

I have on hand MMBT394, I assume I can use them? Looks like they have better ratings.

73

Ken VA3ABN
BC849 replacement

 

I need to replace one of the BC849 transistors in the VFO circuit.

I have on hand MMBT394, I assume I can use them? Looks like they have better ratings.

73

Ken VA3ABN
Re: power for qrp-labs dds

 

Art,

I am assuming you are building your own;

?

I used an LM7808 ?(8v) regulator into the Nano (Arduino), and use the 5v out of the Nano to power the DDS /LCD (if you're building your own)

?

I have also used these successfully to help eliminate noise;

http://www.xppower.com/pdfs/SF_IV.pdf

to power a noisy OLED display - but they are not cheap and you need to be aware of your power requirements.

Rgds,
Darryl

?

?

On 2017-01-24 11:15 AM, Art Olson via Groups.Io wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
Re: (Raduino) A Duhhh.... Moment

 

Got it! Thanks Marco
Re: power for qrp-labs dds

 

¿ªÔÆÌåÓý

Great suggestions. Will give it a try

Thanks

Art

Sent from my iPhone

On Jan 23, 2017, at 7:42 PM, M Garza <mgarza896@...> wrote:

Hi Art,
What is wrong with using a 7805 to provide the 5 volts?? It should not create any noise.

Marco - KG5PRT?

On Jan 23, 2017 6:15 PM, "Art Olson via Groups.Io" <olsonaj6927=[email protected]> wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
Re: power for qrp-labs dds

M Garza
 

Hi Art,
What is wrong with using a 7805 to provide the 5 volts?? It should not create any noise.

Marco - KG5PRT?

On Jan 23, 2017 6:15 PM, "Art Olson via Groups.Io" <olsonaj6927=[email protected]> wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
Re: (Raduino) A Duhhh.... Moment

M Garza
 

Jason,
The toroid is an "extra" part now.? You can keep it to go back to the original vfo or you can use the toroid for something else.

Marco - KG5PRT?

On Jan 23, 2017 6:13 PM, "Janson Sloughter" <janson@...> wrote:
Ok, I see where to cap goes, totally missed that at first.? Just wondering on the 50 turn torroid now.

Re: power for qrp-labs dds

 

¿ªÔÆÌåÓý

Use a 5 volt 3 pin regulator, powered from the 12 volt rail?


On 24/01/2017 11:15 AM, Art Olson via Groups.Io wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
Re: power for qrp-labs dds

 

¿ªÔÆÌåÓý

Art,

I built a small board with a 7805 on it.? Haven't tested it yet.

73,? George


On 1/23/2017 6:15 PM, Art Olson via Groups.Io wrote:

the Bitx40 uses 12v natively however the qrp-labs DDs vfo requires 5 volts. I have tried several buck converters but there is a lot of hashing (noisy) when the converter is powered on. Anyone have a suggestion as to anything I might try. If I use an external 5 volt wall wart then the problem (noise)?goes away. I don't want to have a 12 v power connection and have to run a wall wart also.

73

art
Re: Different display issues

Jack Purdum
 

Thanks Darryl...that gives me something to check into...it's appreciated!

Jack, W8TEE

From: Darryl Harvey <darryl@...>
To: [email protected]
Sent: Monday, January 23, 2017 3:36 PM
Subject: Re: [BITX20] Different display issues

Hi Jack,
I have been battling "noise clicks" for some time now in my DDS. I have tracked it to the i2c bus SDA data being injected in the power rail by my OLED display, the bitx is so sensitive it acts on this noise, my Mst3 with the exact same DDS doesn't have this problem.?

Anyway, the only way I could reduce this noise after many tests and redesigns was to put a D.C.-D.C. Isolator in the power rail for my OLED display. it didn't remove it 100%, more like around 95% - but at least it was usable.?
A simple voltage regulator (7805) and associated filter caps and even chokes didn't help.?

Even though the clicks occur when moving the encoder, it was the display updates causing the noise for me. ?When I moved to a TFT or LCD display I didn't have this issue, but check that your voltage supply to the DDS is not under load, that could cause some noise on updates.

Hope this helps
Darryl
VK3DAZ


On 24 Jan 2017, at 6:39 am, Jack Purdum via Groups.Io <econjack@...> wrote:

All:

I have my B40 with Raduino display and it works as advertised. I am now trying to add my TFT display and DDS VFO, which is a AD9850, more-or-less the same as the VFO in the Forty-9er article (March, 2016 QST). I am using a rotary encoder to change the frequency, again the same as before. The processor is a Mega 2560 Pro Mini; too many things going on for a Nano. I've used the TFT display, DDS, and Mega boards on an antenna analyzer project and had no issues. (Schematic attached, the SWR bridge is omitted.) However, on the B40, any movement of the encoder can be "heard" in the receiver audio. Also, there is a slight dimming, or flicker, of the display when rotating the encoder.?

As I've said many times before, I'm a software guy so the EE stuff leaves me not knowing where to begin. Any ideas sincerely appreciated.


Jack, W8TEE
<Figure33.jpg>
96001 - 96020 of 116566